There is a spectrum of electromagnetic radiation striking the earth on a daily basis originating from the sun. The electromagnetic radiation includes commonly known spectra such as the visible and ultraviolet regions, for example.
The full spectrum is characterized by the term EOF representing the electro optical frequencies of solar radiation. The bands of these frequencies are characterized based upon wavelengths into nine general regions illustrated by the solar spectrum. These nine categories of increasing wavelength from 100 nm to 1 mm include ultraviolet C, ultraviolet B, ultraviolet A, visible light, infrared A, infrared B, infrared C, far infrared, and extreme far infrared.
The extreme far infrared is part of the terahertz spectrum. This special region known as terahertz spectrum radiation or the terahertz gap falls between electromagnetic frequencies (measured with antennas) and optical frequencies (measured with optical detectors). There are currently no known natural sources of terahertz radiation in the extreme far infrared region.
Terahertz radiation is a non-ionizing sub-millimeter radiation and shares with X-rays the capability to penetrate a wide variety of non-conductive materials. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, and plastic. It can also penetrate fog and clouds, but cannot penetrate metal or water.
Terahertz radiation is not expected to damage tissues and DNA unlike X-rays. Some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content and are reflected back. Terahertz radiation is being studied more and more these days in the fields of medical imaging, biochemistry, diagnostics and therapeutics.
U.S. Pat. No. 8,389,035 discloses a method of generating and collecting radiation in the terahertz range of the extreme far infrared region. The '035 patent is assigned to the current assignee of the present disclosure, and is incorporated herein by reference in its entirety. In particular, water is imprinted so as to emit terahertz radiation. The water is imprinted with frequencies from 300 GHz to 3 THz using a polarizing filter through which the polarized radiation passes into the water. Imprinted water may be used to reduce the activity of pathogens and maintain the freshness of food products in a closed environment. Even in view of the '035 patent, there is still a need to improve on the use of radiation in the terahertz frequency range.